In a typical twin-engine jet, temperature and humidity within the aircraft's crew/passenger compartment, is controlled by an Environmental Control System (ECS). Air bled from the aircraft engines is supplied to the aircraft's pneumatic system, where the temperature and pressure of the bleed air are regulated to predetermined set points (tempered bleed air). These set points are established to ensure proper performance of the aircraft Ice Protection system throughout the aircraft's operating envelope. The tempered bleed air is further supplied to the ECS to generate heating and cooling air for the crew/passenger compartment.
Notably, however, temperature and pressure set points suitable for the aircraft pneumatic system are significantly higher than those suitable for the ECS. As a result, performance of the ECS system is substantially degraded throughout the entire operating envelope at these pressure and temperature set points.
Accordingly, there is an ongoing need for improved performance of environmental control systems for aircraft.